Ever since it became feasible to use more than a limited range of web safe fonts, web designers have been merrily unleashing their creativity, using weird and wonderful typefaces without having to resort to imagery.
And ever since then, the people who care about web performance have been trying to curb some of that enthusiasm. This is because a custom font is an extra resource that the browser has to download for the page to be displayed (different browsers do different things in terms of what they’ll display while waiting for a font to load).
We’ve given a broad outline of how to minimise the impact of custom fonts on performance in a previous post. This time, we’re going to focus on one technique: using the unicode-range CSS descriptor for subsetting.